Hairpin winding electric machine

ABSTRACT

An electric machine includes a stator core and hairpin windings. The stator core defines slots that are circumferentially arranged between an inner diameter and an outer diameter of the stator core. Each slot has a plurality of pin positions that is arranged in a direction that extends from the inner diameter of the stator core toward the outer diameter of the stator core. The hairpin windings have a plurality of electrical paths of interconnected hairpins disposed within the slots. Each of the plurality of electrical paths of interconnected hairpins have a plurality of typical hairpins and a plurality of atypical hairpins. Each typical hairpin has first and second opposing inwardly extending twist portions. Each atypical hairpin has a third inwardly extending twist portion and an outwardly extending twist portion disposed on an opposing end of the atypical hairpin relative to the third inwardly extending twist portion.

TECHNICAL FIELD

The present disclosure relates to electric machines and morespecifically to electric machines that include hairpin windings.

BACKGROUND

Vehicles such as battery-electric vehicles and hybrid-electric vehiclescontain a traction-battery assembly to act as an energy source for thevehicle. The traction battery may include components and systems toassist in managing vehicle performance and operations. The tractionbattery may also include high-voltage components, and an air or liquidthermal-management system to control the temperature of the battery. Thetraction battery is electrically connected to an electric machine thatprovides torque to driven wheels. Electric machines typically include astator and a rotor that cooperate to convert electrical energy intomechanical motion or vice versa.

SUMMARY

An electric machine includes a stator core and hairpin windings. Thestator core defines slots that are circumferentially arranged between aninner diameter and an outer diameter of the stator core. Each slot has aplurality of pin positions that is arranged in a direction that extendsfrom the inner diameter of the stator core toward the outer diameter ofthe stator core. The hairpin windings have a plurality of electricalpaths of interconnected hairpins disposed within the slots. Each of theplurality of electrical paths of interconnected hairpins have aplurality of typical hairpins and a plurality of atypical hairpins. Eachtypical hairpin has a crown pitch of eight, nine, or ten, slots andopposing inwardly extending twist pitches along each end of the typicalhairpin of four and one half slots. Each atypical hairpin has aninwardly extending twist pitch and an outwardly extending twist pitch onopposing respective ends of the atypical hairpin.

An electric machine includes a stator core and hairpin windings. Thestator core defines slots that are circumferentially arranged between aninner diameter and an outer diameter of the stator core. Each slot has aplurality of pin positions that is arranged in a direction that extendsfrom the inner diameter of the stator core toward the outer diameter ofthe stator core. The hairpin windings have a plurality of electricalpaths of interconnected hairpins disposed within the slots. Each of theplurality of electrical paths of interconnected hairpins have aplurality of typical hairpins and a plurality of atypical hairpins. Eachtypical hairpin has first and second opposing inwardly extending twistportions. Each atypical hairpin has a third inwardly extending twistportion and an outwardly extending twist portion disposed on an opposingend of the atypical hairpin relative to the third inwardly extendingtwist portion. Each of the atypical hairpins is disposed along an innerdiameter or an outer diameter of the hairpin windings.

An electric machine includes a stator core and hairpin windings. Thestator core defines fifty-four slots that are circumferentially arrangedbetween an inner diameter and an outer diameter of the stator core. Eachslot has six pin positions that are arranged in a direction that extendsfrom the inner diameter of the stator core toward the outer diameter ofthe stator core. The hairpin windings having three electrical phases.Each electrical phase has three parallel electrical paths ofinterconnected hairpins disposed within the slots. Each of theelectrical paths of interconnected hairpins has first, second, third,and fourth types of hairpins. Each of the first type of hairpins has afirst crown portion spanning eight slots and first and second opposinginwardly extending twist portions. Each of the first and second twistportions span four and one half slots. Each of the second type ofhairpins has a second crown portion spanning nine slots and third andfourth opposing inwardly extending twist portions. Each of the third andfourth twist portions span four and one half slots. Each of the thirdtype of hairpins has a third crown portion spanning ten slots and fifthand sixth opposing inwardly extending twist portions. Each of the fifthand sixth twist portions span four and one half slots. Each of thefourth type of hairpins has a fourth crown portion spanning nine slots,a seventh inwardly extending twist portion, and an outwardly extendingtwist portion on an opposing side of the fourth crown portion relativeto the seventh inwardly extending twist portion. Each of the seventhinwardly extending twist portions and outwardly extending twist portionsspan four and one half slots.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an electric machine;

FIG. 2 is a cross-sectional end view of a stator of the electricmachine;

FIG. 3 is a magnified view of a portion of FIG. 2 ;

FIG. 4 is a front view of a generic hairpin;

FIG. 5 is a front view of a typical hairpin of a first type;

FIG. 6 is a front view of a typical hairpin of a second type;

FIG. 7 is a front view of a typical hairpin of a third type;

FIG. 8 is a front view of an atypical hairpin;

FIG. 9 is a winding diagram of a first of three phases of the statorwinding;

FIG. 10 is a winding diagram of a second of three phases of the statorwinding;

FIG. 11 is a winding diagram of a third of three phases of the statorwinding;

FIG. 12 is a perspective view of one of three phases of the statorwinding; and

FIG. 13 is a perspective view of all three phases of the stator winding.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments may take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the embodiments. Asthose of ordinary skill in the art will understand, various featuresillustrated and described with reference to any one of the figures maybe combined with features illustrated in one or more other figures toproduce embodiments that are not explicitly illustrated or described.The combinations of features illustrated provide representativeembodiments for typical applications. Various combinations andmodifications of the features consistent with the teachings of thisdisclosure, however, could be desired for particular applications orimplementations.

Referring to FIG. 1 , an electric machine 20 may be used in a vehiclesuch as a fully electric vehicle or a hybrid-electric vehicle. Theelectric machine 20 may be referred to as an electric motor, a tractionmotor, a generator, or the like. The electric machine 20 may be apermanent magnet machine, an induction machine, or the like. In theillustrated embodiment, the electric machine 20 is a three-phasealternating current (AC) machine. The electric machine 20 is capable ofacting as both a motor to propel the vehicle and as a generator such asduring regenerative braking.

The electric machine 20 may be powered by an electrical power sourcesuch as a traction battery of the vehicle. The traction battery maysupply a high-voltage direct current (DC) output from one or morebattery-cell arrays, sometimes referred to as battery-cell stacks,within the traction battery. The battery-cell arrays may include one ormore battery cells that convert stored chemical energy to electricalenergy. The cells may include a housing, a positive electrode (cathode),and a negative electrode (anode). An electrolyte allows ions to movebetween the anode and cathode during discharge, and then return duringrecharge. Terminals allow current to flow out of the cells for use bythe vehicle.

The traction battery may be electrically connected to one or more powerelectronics modules. The power electronics modules may be electricallyconnected to the electric machines 20 and may provide the ability tobi-directionally transfer electrical energy between the traction batteryand the electric machine 20. For example, a suitable traction batterymay provide a DC voltage while the electric machine 20 may require athree-phase (AC) voltage. The power electronics module may include aninverter that converts the DC voltage to a three-phase AC voltage asrequired by the electric machine 20. In a regenerative mode, the powerelectronics module may convert the three-phase AC voltage from theelectric machine 20 acting as a generator to the DC voltage required bythe traction battery.

Referring to FIGS. 1 and 2 , the electric machine 20 may include ahousing 21 that encloses the stator 22 and the rotor 24. The stator 22is fixed to the housing 21 and includes a cylindrical stator core 32having an inner diameter (ID) 28 that defines a hole 30 and an outerdiameter (OD) 29. The stator core 32 may be formed from a plurality ofstacked laminations. The rotor 24 is supported for rotation within thehole 30. The rotor 24 may include windings or permanent magnets thatinteract with windings of the stator 22 to generate rotation of therotor 24 when the electric machine 20 is energized. The rotor 24 may besupported on a shaft 26 that extends through the housing 21. The shaft26 may be supported by bearings (not shown) that are secured to thehousing 21 such that the rotor 24 and shaft 26 may rotate relative tothe housing 21 and stator 22. The shaft 26 is configured to couple witha drivetrain of the vehicle to output torque for vehicle propulsion orreceive mechanical regenerative energy from vehicle motion.

The stator core 32 defines circumferentially-arranged slots 34 (seee.g., FIG. 2 ) around the stator core 32 and extending outward from theinner diameter 28. The slots 34 may be equally spaced around thecircumference, may be circumferentially arranged between the innerdiameter 28 and the outer diameter 29 of the stator core 32 (e.g., theslots 34 may extend radially from the inner diameter 28 to the outerdiameter 29 of the stator core 32), and may extend axially from a firstend 36 of the stator core 32 to a second end 38. Each slot 34 has aplurality of pin positions that is arranged in a direction that extendsfrom the inner diameter 28 toward the outer diameter 29 of the statorcore. In the illustrated embodiment, the stator core 32 definesfifty-four slots. Each of the three electrical phases is formed byhairpin windings 40 that are disposed within the fifty-four slots. Thehairpin windings 40 of each phase form six poles. Each pole includes aportion of the hairpin windings 40 that occupies three consecutive slotsof the fifty-four slots.

The slots 34 are spaced by a circumferential distance measured betweenthe center lines of two adjacent slots. This distance can be used as aunit of distance (hereinafter “a slot”) for relating to, and measuring,other components of the stator 22. The distance unit “slot” is alsosometimes referred to as “slot pitch” or “slot span.” The slots 34 arealso referenced by numbers 1 through 54 in the counterclockwisedirection with the odd number slots being labeled for convenience. Theslots may be characterized as odd slots (i.e., slots 1, 3, 5, etc.) andeven slots (i.e., slots 2, 4, 6, etc.). The odd and even designation isfor ease of description in explaining the arrangement of the windings40, and the structure of odd and even slots may be the same.

The electric machine 20 includes hairpin windings 40 routed through theslots 34 of the stator core 32. Hairpin winding configurations canimprove efficiency for electric machines used in vehicles as well asother applications. The hairpin windings 40 improve efficiency byproviding a greater amount of stator conductors to reduce resistance ofthe winding 40 without encroaching into space reserved for theelectrical steel and the magnetic flux path. Each of the threeelectrical phases is formed by the hairpin windings 40 that are disposedwithin the slots 34. The hairpin windings 40 of each of the threeelectrical phase forms six poles. Each pole includes a portion of thehairpin windings 40 that occupies three sequential or three consecutiveslots 34.

Using three slots per pole per phase helps to reduce the unwantedharmonics at the expense of a more complicated winding structure. Tomake a motor with a desired current and voltage ratings, it is oftenrequired to connect the hairpin windings in different series and/orparallel combinations. One challenge in such operation is to achieve abalanced parallel path that does not produce a circulating currentbetween the parallel paths. The task becomes more challenging forhairpin windings, as the rigid hairpins are may not be suitable forproducing random connections between pins. It necessitates a carefulwinding design that can produce balanced parallel circuitry withoutrequiring substantial manufacturing complexity. A balanced windingtopology that includes three slots per pole per phase is describeherein. More specifically, three balanced paths per phase are utilized.The three paths share a comparable number of slots occupancy in the IDand OD regions of the stator 22. The three paths also share comparableslot occupancy along all circumferential directions in order to avoid animbalance due to manufacturing tolerance or due to rotor imbalance.

The electric machine 20 may be a three-phase current electric machine inwhich the hairpin windings 40 are arranged in a U phase, a V phase, anda W phase. The phases may be referred to first, second, and third phasesin any order. In the examples of the present disclosure, each phaseincludes a plurality of individual hairpin conductors arranged inparallel winding paths.

Referring to FIG. 3 , the slots 34 may include an inner radial layer 170of hairpins, a middle radial layer 172 of hairpins, and an outer radiallayer 174 of hairpins. Each of the layers may include at least tworadial pin positions that are adjacent to each other. In the illustratedembodiment, each slot 34 has six sequential pin positions (i.e., L1through L6) in a one-by-six linear arrangement, however, otherarrangements are contemplated. The first position L1, is nearest the ID28 of the stator core 32 and the sixth position L6 is nearest the OD 29of the stator core 32. The innermost radial layer 170 includes both thefirst position L1 and the second position L2. The middle radial layer172 includes both the third position L3 and the fourth position L4. Theoutermost radial layer 174 includes both the fifth position L5 and thesixth position L6.

Referring to FIG. 4 , a generic hairpin is schematically depicted toshow the general configuration. The hairpins are generally U-shaped andinclude a pair of legs joined by a crown. Each of a plurality ofhairpins are installed in the stator core 32 by routing each leg portionthrough a corresponding one of the slots 34. Each hairpin may beinstalled from the same end of the stator core 32 (e.g., from end 36) sothat once installed all of the crowns are located on one end of thestator, and the ends of the legs all are located on the opposing end(e.g., end 38). Generally, end 36 may be referred to as the crown endand end 38 may be referred to as the weld end. Once installed, the legsof the hairpins are bent away from each other to form twists thatconnect with the twists of other hairpins. The ends of correspondinghairpins are joined by an electrically conductive connection such as aweld. The connections may be arranged in rows. The windings 40 may bejumper-less (i.e., each hairpin is interconnected to another hairpindirectly) or may include a minimum number of jumpers. A jumper is aconductor that is typically disposed at one of the ends of the statorcore, i.e., does not extend through a slot, and interconnects hairpinsthat are spaced far enough apart that they cannot be directly connectedto each other. Jumpers add material to the windings and requireadditional manufacturing. Material usage can be reduced, andmanufacturing efficiencies can be gained, by designing windings that donot require jumpers or only have a minimum number of jumpers.

Each arrangement may include hairpins as described in FIG. 4 . Hairpin90 may be formed from a single piece of metal such as copper, aluminum,silver, or any other electrically conductive material. The hairpin 90may include a first leg 98 joined to a second leg 100 at a vertex 102.The first leg 98 is disposed within in one of the slots 34 and thesecond leg 100 is disposed in another of the slots 34 that is spacedapart by a span of slots. The span of slots 34 between the first leg 98and the second leg 100 may be referred to as the crown pitch. The firstleg 98 includes a straight portion 99 disposed within a slot 34 and afirst angled portion 104 that extends between the vertex 102 and thestraight portion 99. The straight portion 99 and the angled portion 104are joined at a first bend 106. The first leg 98 also includes a twistportion 110 that is angled outward at a second bend 108. The second leg100 includes a straight portion 101 disposed within a slot 34 and afirst angled portion 112 that extends between the vertex 102 and thestraight portion 101. The first and second angled portions 104, 112 andthe vertex 102 may be collectively referred to as a crown. The straightportion 101 and the angled portion 112 are joined at a first bend 114.The second leg 100 also includes a twist portion 120 that is angledoutward at a second bend 118. The twists 110, 120 are angled in opposingdirections to extend outward and away from the crown of the hairpin 90to connect with adjacent pins of the wiring path. Some hairpins,however, may have one or more twists that are angled inward and towardthe crown the crown of the hairpin. The span of slots 34 of the twists110, 120 from the respective straight portions 99, 101 to the respectiveends of the twists 110, 120 may be referred to as the twist pitches.Twist portions that are angled outward, as illustrated in FIG. 4 , maybe said to have a positive twist pitch and twist portions that areangled inward may be said to have a negative twist pitch.

The hairpin 90 may be fabricated by first forming the vertex 102, thefirst angled portions 104, 112, and two extended straight portions.Then, the hairpin 90 is installed into the stator 22 by inserting theextended straight portions into the slots 34 of the stator 22. Thesecond bends 108, 118 and the twists 110, 120 may be formed after thehairpin 90 is installed through the slots 34 by bending the extendedlegs as desired. The first and last regular pins of a wiring path mayhave a longer or shorter twist to facilitate connection with theterminal leads or neutral connections.

A neutral connection 52 may include a body such as a strip of conductivemetal or other material. The neutral connection 52 includes openingsthat connect with hairpins. In the examples of the present disclosure,the neutral connection defines nine openings grouped as sets of three.Each of the groupings are associated with one of the phases such thateach of the U phase, the V phase, and the W phase are allocated threeopenings. The neutral connection 52 may be connected directly to thetwist portions of hairpins that are positioned at a most radiallyoutward position of the hairpins (i.e., the neutral connection may beconnected to hairpins located at the sixth position L6). The twistportions that connect to the neutral connection 52 may not need to belengthened to accommodate the weld portion since there may be sufficientclearance for the neutral connection 52 to be attached to the outside ofthe most radially outward hairpins.

Referring to FIGS. 5-8 , various types of hairpins that are utilized toform the hairpin windings 40 are illustrated. FIGS. 5-7 depict typicalhairpins that have inwardly extending twist portions (i.e., twistportions with a negative twist pitch) while FIG. 8 depicts an atypicalhairpin having one inwardly extending twist portion and one outwardlyextending twist portion (i.e., a twist portion with a positive twistpitch).

The first type of typical hairpin 130, which is depicted in FIG. 5 , hasa crown portion 132 having a pitch spanning ten slots 34. The first typeof typical hairpin 130 also has first and second inwardly extendingtwist portions 134 each having a pitch spanning four and one half slots34. The second type of typical hairpin 140, which is depicted in FIG. 6, has a crown portion 142 having a pitch spanning nine slots 34. Thesecond type of typical hairpin 140 also has first and second inwardlyextending twist portions 144 each having a pitch spanning four and onehalf slots 34. The third type of typical hairpin 150, which is depictedin FIG. 7 , has a crown portion 152 having a pitch spanning eight slots34. The third type of typical hairpin 150 also has first and secondinwardly extending twist portions 154 each having a pitch spanning fourand one half slots 34.

The atypical hairpin 160, which is depicted in FIG. 8 , has a crownportion 162 having a pitch spanning nine slots 34. The atypical hairpin160 also has an inwardly extending twist portion 164 and an outwardlyextending twist portion 166 disposed on an opposing end of the atypicalhairpin 160 relative to the inwardly extending twist portion 164. Theinwardly extending twist portion 164 has a pitch spanning four and onehalf slots 34. The outwardly extending twist portion 166 also has apitch spanning four and one half slots 34.

Referring now to FIGS. 9-13 , the hairpin windings 40 are illustrated inFurther detail. Each of the hairpins forming the windings 40 has astructure that corresponds to either the typical hairpins depicted inFIG. 5-7 or the atypical harpins depicted in FIG. 8 , with the exceptionof at least some of the hairpins forming the lead connections (i.e., thehairpins connecting the hairpins windings 40 to a power source). A.Winding diagrams of the three electrical phases of the hairpin windings40 are depicted FIGS. 9-11 , with FIG. 9 representing the U-phase, FIG.10 representing the V-phase, and FIG. 11 representing the W-phase. Thephysical structure of the portion of the windings 40 forming the W-phaseis illustrated in FIG. 12 . The entire physical structure of thewindings 40, including all three phases, is illustrated in FIG. 13 . Itshould be noted that the physical structure of each of the phases may beidentical. However, each phase may be positioned within the slots 34such that each phase is offset relative to the other phases. Forexample, (i) the V-phase may be offset from the U-phase via a pitch ofsix slots 34 in a first direction and (ii) the W-phase may be offsetfrom the U-phase via a pitch of twelve slots 34 and offset from theV-phase via a pitch of six slots 34 in the first direction.

For each of the winding diagrams, each column represents a slot locationof the stator stack segments having reference numbers from 1 through 54.The slot locations 1 through 54 are also illustrated in FIGS. 12 and 13. Each row represents a radial layer positioned within each respectiveslot having references L1 toward the inner diameter side through L6toward the outer diameter side. Each phase (i.e., the U-phase, V-phase,and W-phase) includes a plurality of electrical paths formed byinterconnected hairpins of the hairpin windings 40. More specifically,each phase includes a first electrical path 202, a second electricalpath 204, and a third electrical path 206. Each electrical path 202,204, 206 is connected in parallel to a terminal lead 208 at a first endand the neutral connection 52 at a second end. The terminal leads 208may include a body such as a strip of conductive metal or othermaterial. The terminal leads 208 includes openings that connect with thehairpins. Each terminal lead 208 connects one of the phases to a powersource (e.g., a battery via an inverter).

Each electrical path 202, 204, 206 is comprised of a plurality oftypical hairpins (i.e., hairpins 130, 140, and 150) and a plurality ofatypical hairpins (i.e., hairpin 160). The electrical paths 202, 204,206 of each phase are arranged in parallel to each other from arespective terminal lead 208 to the neutral connection 52. A subset ofhairpins 210 form terminal lead connections along an outer periphery,boundary, or diameter of the hairpin windings 40 (e.g., toward the OD ofthe stator core 32) for each electrical path 202, 204, 206. Morespecifically, the subset of hairpins 210 may include the last hairpin ofeach electrical path 202, 204, 206 that connects each electrical path202, 204, 206 to the terminal leads 208.

Each hairpin of the subset of hairpins 210 may be a typical hairpinhaving two inwardly extending twist portions (e.g., U-phase in FIG. 9 )or an atypical hairpin having an inwardly extending twist portion and anoutwardly extending twist portion (e.g., W-phase in FIG. 11 ). However,the twist portion of each hairpin of the subset of hairpins 210 thatconnects to a terminal lead 208 may have a pitch other than four and onehalf slots 34. Furthermore, the subset of hairpins 210 may have a twistportion having a pitch of zero slots 34 that connects to a terminal lead208 (e.g., V-phase in FIG. 10 ). The twist portion of each hairpin ofthe subset of hairpins 210 that connects to an adjacent hairpin may havea pitch of four and one half slots 34. The crown portion of each hairpinof the subset of hairpins 210 may have a pitch of nine slots 34.

The subset of hairpins 210, the terminal leads 208, and the neutralconnection 52 are illustrated as being disposed along an outerperiphery, boundary, or diameter of the hairpin windings 40 (e.g.,toward the OD of the stator core 32). It should be understood, however,that the wiring of each electrical path 202, 204, 206 of each phase maybe reversed or flipped such that the subset of hairpins 210, theterminal leads 208, and the neutral connection 52 are disposed along theinner boundary or diameter of the hairpin windings 40 (e.g., toward theID of the stator core 32). Whether the subset of hairpins 210 aredisposed along the outer periphery, boundary, or diameter of the hairpinwindings or along the inner boundary or diameter of the hairpin windings40, the remainder of hairpins along the inner and outer periphery,boundary, or diameter of the hairpin windings 140 are atypical hairpins160. The hairpins forming one or more middle layers that are disposedbetween the inner and outer periphery, boundary, or diameter of thehairpin windings 140 are typical hairpins, which may be arranged ingroups of three with one of each of the first, second, and third typesof typical hairpins 130, 140, 150 (i.e., one with a crown pitch of ten,one with a crown pitch of nine, and one with a crown pitch of eight) andone from each electrical path 202, 204, 206.

Within each wiring diagram, the crowns portions of the hairpins areillustrated as dashed lines, the twist portions are illustrated as asolid lines, and the lines that extend in an almost straight, butslightly angled, direction between the ID to the OD represent wheretwist portions of adjacent hairpins are connected to each other. Theslot position 1 through 54 that correspondents to a transition between acrown portion and a twist portion represents the slot where a straightportion (e.g., straight portion 99 or straight portion 101) of acorresponding hairpin is disposed.

Referring specifically to FIG. 12 , each pole 212 may be represented bythe portions of the hairpins of each phase that occupy three consecutiveslots of the fifty-four slots. Each phase in turn forms a total of sixpoles. Although the poles 212 may be represented by the portions of thehairpins of each phase that occupy three consecutive slots, each polemay technically comprise the large loops 214 formed by the hairpins.

It should be understood that the designations of first, second, third,fourth, etc. for any component, state, or condition described herein maybe rearranged in the claims so that they are in chronological order withrespect to the claims. Furthermore, it should be understood that anycomponent, state, or condition described herein that does not have anumerical designation may be given a designation of first, second,third, fourth, etc. in the claims if one or more of the specificcomponent, state, or condition are claimed.

The words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments may becombined to form further embodiments that may not be explicitlydescribed or illustrated. While various embodiments could have beendescribed as providing advantages or being preferred over otherembodiments or prior art implementations with respect to one or moredesired characteristics, those of ordinary skill in the art recognizethat one or more features or characteristics may be compromised toachieve desired overall system attributes, which depend on the specificapplication and implementation. As such, embodiments described as lessdesirable than other embodiments or prior art implementations withrespect to one or more characteristics are not outside the scope of thedisclosure and may be desirable for particular applications.

What is claimed is:
 1. An electric machine comprising: a stator coredefining slots that are circumferentially arranged between an innerdiameter and an outer diameter of the stator core, each slot having aplurality of pin positions that is arranged in a direction that extendsfrom the inner diameter of the stator core toward the outer diameter ofthe stator core; and hairpin windings having a plurality of electricalpaths of interconnected hairpins disposed within the slots, each of theplurality of electrical paths of interconnected hairpins having aplurality of typical hairpins and a plurality of atypical hairpins,wherein (i) each typical hairpin has a crown pitch of eight, nine, orten, slots and opposing inwardly extending twist pitches along each endof the typical hairpin of four and one half slots and (ii) each atypicalhairpin has an inwardly extending twist pitch and an outwardly extendingtwist pitch on opposing respective ends of the atypical hairpin.
 2. Theelectric machine of claim 1, wherein a subset of hairpins forms terminallead connections along an inner diameter or an outer diameter of thehairpin windings.
 3. The electric machine of claim 2, wherein theremainder of the hairpins along the inner and outer diameters of thehairpin windings are each atypical hairpins.
 4. The electric machine ofclaim 2, wherein a portion of the subset of hairpins are atypicalhairpins.
 5. The electric machine of claim 1, wherein (i) the hairpinwindings form three electrical phases and (ii) each electrical phase iscomprised of three of the plurality of electrical paths ofinterconnected hairpins.
 6. The electric machine of claim 5, whereinthree electrical paths of interconnected hairpins of each electricalphase are arranged in parallel relative to each other.
 7. The electricmachine of claim 5, wherein each electrical phase has six poles, andwherein each pole is comprised of a portion of the interconnectedhairpins that occupy three consecutive slots.
 8. The electric machine ofclaim 1, wherein a subset of hairpins disposed in a middle layer betweenan inner diameter and an outer diameter of the hairpin windings arearranged in groups of three, (ii) each hairpin of each group of three isfrom a different electrical path of the plurality of electrical paths,and (iii) each group of three includes one hairpin having a crown pitchof eight, one hairpin having a crown pitch of nine, and one hairpinhaving a crown pitch of ten.
 9. An electric machine comprising: a statorcore defining slots that are circumferentially arranged between an innerdiameter and an outer diameter of the stator core, each slot having aplurality of pin positions that is arranged in a direction that extendsfrom the inner diameter of the stator core toward the outer diameter ofthe stator core; and hairpin windings having a plurality of electricalpaths of interconnected hairpins disposed within the slots, each of theplurality of electrical paths of interconnected hairpins having aplurality of typical hairpins and a plurality of atypical hairpins,wherein (i) each typical hairpin has first and second opposing inwardlyextending twist portions, (ii) each atypical hairpin has a thirdinwardly extending twist portion and an outwardly extending twistportion disposed on an opposing end of the atypical hairpin relative tothe third inwardly extending twist portion, and (iii) each of theatypical hairpins is disposed along an inner diameter or an outerdiameter of the hairpin windings.
 10. The electric machine of claim 9,wherein each typical hairpin has a crown that spans eight, nine, or tenslots.
 11. The electric machine of claim 10, wherein the first andsecond opposing inwardly extending twist portions of each typicalhairpin spans four and one half slots.
 12. The electric machine of claim9, wherein each atypical hairpin has a crown that spans nine slots, andwherein the third inwardly extending twist portion of each atypicalhairpin spans four and one half slots.
 13. The electric machine of claim9, wherein a subset of hairpins disposed in a middle layer between aninner diameter and an outer diameter of the hairpin windings arearranged in groups of three, (ii) each hairpin of each group of three isfrom a different electrical path of the plurality of electrical paths,and (iii) each group of three includes one hairpin having a crown pitchof eight, one hairpin having a crown pitch of nine, and one hairpinhaving a crown pitch of ten.
 14. The electric machine of claim 9,wherein a subset of hairpins forms terminal lead connections along aninner diameter or an outer diameter of the hairpin windings.
 15. Theelectric machine of claim 14, wherein the remainder of the hairpinsalong the inner and outer diameters of the hairpin windings are eachatypical hairpins.
 16. An electric machine comprising: a stator coredefining fifty-four slots that are circumferentially arranged between aninner diameter and an outer diameter of the stator core, each slothaving six pin positions that are arranged in a direction that extendsfrom the inner diameter of the stator core toward the outer diameter ofthe stator core; and hairpin windings having three electrical phases,each electrical phase having three parallel electrical paths ofinterconnected hairpins disposed within the slots, each of theelectrical paths of interconnected hairpins having first, second, third,and fourth types of hairpins, wherein (i) each of the first type ofhairpins has a first crown portion spanning eight slots and first andsecond opposing inwardly extending twist portions, each of the first andsecond twist portions spanning four and one half slots, (ii) each of thesecond type of hairpins has a second crown portion spanning nine slotsand third and fourth opposing inwardly extending twist portions, each ofthe third and fourth twist portions spanning four and one half slots,(iii) each of the third type of hairpins has a third crown portionspanning ten slots and fifth and sixth opposing inwardly extending twistportions, each of the fifth and sixth twist portions spanning four andone half slots, and (iv) each of the fourth type of hairpins has afourth crown portion spanning nine slots, a seventh inwardly extendingtwist portion, and an outwardly extending twist portion on an opposingside of the fourth crown portion relative to the seventh inwardlyextending twist portion, each of the seventh inwardly extending twistportions and outwardly extending twist portions spanning four and onehalf slots.
 17. The electric machine of claim 16, wherein a subset ofhairpins forms terminal lead connections along an inner diameter or anouter diameter of the hairpin windings.
 18. The electric machine ofclaim 17, wherein the remainder of the hairpins along the inner andouter diameters of the hairpin windings are the fourth type of hairpins.19. The electric machine of claim 16, wherein a subset of hairpinsdisposed in a middle layer between an inner diameter and an outerdiameter of the hairpin windings of each electrical phase are arrangedin groups of three, (ii) each hairpin of each set of three is from adifferent electrical path of the three parallel electrical paths of eachphase, and (iii) each set of three includes one hairpin having a crownpitch of eight, one hairpin having a crown pitch of nine, and onehairpin having a crown pitch of ten.
 20. The electric machine of claim16, wherein (i) each electrical phase has six poles and (ii) each poleis comprised of a portion of the interconnected hairpins that occupythree consecutive slots.